Surface Analysis of an Elongated Object

Abstract

A number of luminous sources ( 4 ) are arranged in a ring-shaped manner in a plane and individually and successively emit, in a rotating manner on the ring, an incident beam oriented toward the axis ( 5 ) of the ring and diagonal to this axis at an angle that is not a right angle. This beam is reflected by the object ( 2 ) placed essentially along the axis ( 5 ), whereupon it is received by one of the photodetectors ( 8 a, 8 b, 8 c ) situated in a plane parallel to the ring of sources. The presence of a shape defect of a surface irregularity or of a variation in color is determined by modulating the energy received by the photodetectors. This measure provides a very good resolution of the successive lighting of very small areas of the object surface.

1 . A device for analyzing the surface condition of an elongated object such as a wire or similar, comprising: 
 a plurality of light sources arranged roughly in a ring in a plane, said sources being designed each to emit a main incident beam oriented towards the axis of the ring, and being arranged so that the main incident beams form with the axis of the ring an angle that is not a right angle and not a zero angle, the object being intended to be placed in the vicinity of said axis such that an area to be analyzed of the surface of said object is placed on the path of the incident beams;    at least three photodetectors located in a plane roughly parallel to the ring of the sources, the photodetectors being positioned such that each reflected beam formed by the direct and perfect reflection on the object of an incident beam can be received by at least two of the three photodetectors;    wherein it comprises means intended to provoke the individual and successive activation of the sources in a localized and rotating manner on the ring, in order to generate a rotating incident beams to provoke rotating reflections on the surface of the object towards the photodetectors.    
   
   
       2 . The device as claimed in  claim 1 , wherein it also comprises a lens placed between each photodetector and the point of intersections between the main incident beams and the axis of the ring, to collect the energy reflected by the object and direct it to the photodetectors.  
   
   
       3 . The device as claimed in  claim 1 , wherein it comprises at least ten sources distributed roughly equidistant in a ring.  
   
   
       4 . The device as claimed in  claim 1 , wherein it comprises a toric lens placed between the ring of the sources and the axis of the ring, centered on said axis, making it possible to concentrate the incident beams into a fine line in the vicinity of the axis.  
   
   
       5 . The device as claimed in  claim 1 , wherein it comprises at least three photodetectors spaced at regular angles to each other.  
   
   
       6 . The device as claimed in  claim 1 , wherein it comprises a device for acquiring and comparing signals from the photodetectors making it possible to measure the variations of the energy received by the photodetectors, locate their origin on the surface of the object and dimension the defects.  
   
   
       7 . A method of analyzing the surface condition of an elongated object such as a wire or similar, comprising steps consisting in: 
 providing a plurality of light sources placed roughly in a ring, said sources being designed each to emit an incident beam oriented towards the axis of the ring and forming with said axis an angle that is not a right angle and not a zero angle;    placing the object roughly on the axis of the ring, a roughly annular area to be analyzed of the surface of the object being placed on the path of the incident beams;    providing at least three photodetectors located in a plane roughly parallel to the ring of the sources, said photodetectors being positioned so that each reflected beam formed by the direct and perfect reflection on the object of an incident beam can be received by at least two of the three photodetectors;    individually and successively activating the sources, in a rotating manner on the ring, to produce a circumferential sweep of the reflections on the surface of the object received by the photodetectors which measure the received energy point-by-point.    
   
   
       8 . The method as claimed in  claim 7 , wherein a change of the surface condition, the presence of a defect of shape, an irregularity on the surface of the object, or a modification of the color of the surface of the object, is determined by measuring the variation of the energy reflected and received by at least two photodetectors.  
   
   
       9 . The method as claimed in  claim 7  wherein it also comprises the step consisting in progressively displacing the object along the axis of the ring in order to analyze all the surface of the object by spiral scanning.